JohnN....I just replaced an XM L2 module in a Solar Force L2M with the lower power option (.8 to 4.2v) XP-G module which has a low voltage shut down circuit for use with Li-ion 18650s...with a smooth reflector, this has become one of my favorites...
http://www.solarforceflashlight-sales.com/product_detail.php?t=RB&s=10&id=210